Innovative, complex computer-generated monaural and dichotic stimuli will be employed to study processes of concurrent auditory grouping and figural emphasis, and several kinds of echoic memory which underly non-concurrent (i.e., temporal) grouping. The limits of the capability of the auditory system to perform grouping will be probed, as will many interactions among grouping cues. The auditory system's ability to use one cue to either camouflage or facilitate the action of another, will be studied. The results of these experiments are expected to clarify the relationship between pre-attentive processes and attention, as well as the analogy between auditory and visual grouping phenomena.